News

Bay Bridge bolt maker says report 'exonerates' it from blame

By Lisa Vorderbrueggen and Matthias GafniContra Costa Times

Posted:
05/24/2013 06:02:12 AM PDT

Updated:
05/24/2013 06:02:18 AM PDT

Click photo to enlarge

An acoustic sensor is attached to an anchor rod securing a critical shear key on the new Bay Bridge Friday afternoon May 3, 2013. Caltrans is using acoustic and hardness monitors to determine if the remaining anchor rods that did not snap are viable. (Karl Mondon/Bay Area News Group)

OAKLAND -- As work started Thursday on repairs for the failed anchor rods on the new eastern span of the Bay Bridge, the Ohio manufacturer of 288 massive steel bolts -- including 32 that snapped in March -- broke its silence with a top sales executive saying a recent report "exonerates" the company from blame.

Dyson Corp. President Brian Rawson also released a video statement that cited a May 7 peer review report commissioned by Caltrans, in which three metallurgists concluded the snapped bolts met Caltrans' specifications.

"We produce products to very precise international standards that are specified by our customer's engineers," Rawson said in the video released via PRWeb. "Through this report and mutual internal investigations, it was concluded that the Dyson Corporation met its requirements to manufacturing anchor rods to the specifications requested."

A broken anchor rod rises up next to still-tensioned rods on a shear key on the new Bay Bridge Friday afternoon May 3, 2013. Caltrans showed off the rods and some of the techniques they are using to monitor and test other installed anchor rods as they design a fix for the compromised hardware. (Karl Mondon/Bay Area News Group)

A team of Caltrans engineers and metallurgical experts have spent the past two months trying to determine why 32 of 96 high-strength steel bolts installed in a key seismic feature on the new bridge suffered from hydrogen embrittlement and who is responsible.

Documents released by Caltrans this week reveal that the bridge design team ordered high-strength bolts for the seismic shear keys and other areas of the bridge, despite warnings by the American Society for Testing and Materials group that hot-dip galvanizing the stronger grade of steel could make it susceptible to hydrogen embrittlement -- a condition where hydrogen atoms invade the steel and make it brittle and subject to fracture.

Advertisement

In a May 17 interview with trade publication American Metal Market, Dustin Johnson, director of sales at the Painesville, Ohio-based fastener systems fabricator, said the company "made the product exactly to the specifications that they asked us." He also said the May 7 report "exonerates" his company.

"Our customers give us the specifications, and we make parts to these specifications," he told the publication.

Caltrans spokesman Will Shuck said Dyson's choice of the word "exonerates" surprised him.

"I don't think we've accused anybody of anything," he said. "Caltrans and the (bridge) partners are focused on their investigation and to moving forward with their solution."

On Thursday afternoon, American Bridge Fluor Joint Venture workers stood on newly installed platforms on the massive pier east of the main span, drilling holes into concrete that they will use to strap down exterior saddles on the two seismic stabilizers to compensate for the broken bolts.

The saddles are designed to carry the load intended for the 96 huge threaded high-strength anchor rods -- 3 inches in diameter and 17 to 24 feet long -- inside shear keys positioned between the pier's columns and the bridge deck. The shear keys and adjacent bearings work together to control movement during an earthquake.

The saddle will cradle 430 steel rope strands made of steel twice as strong as the 96 anchor bolts. The strands will be anchored on the outside of the pier cap and covered with reinforced concrete.

Caltrans estimated the fix could cost as much as $10 million.

XKT Engineering Inc., a steel fabricator on Mare Island in Vallejo, has been selected to make the components. The design is still being tweaked, and it's unclear when the saddle will be finished. The company previously manufactured skyway piles, joints and service platforms on the new bridge.

It still remains unclear if the fix and other tests on steel fasteners on the bridge will be completed in time for the scheduled Sept. 3 bridge opening.